I've been investigating a similar issue with White Noise, which also generates its audio on-the-fly. I use a 2s buffer, or 120 fragments, when the app is not fullscreen.
I actually thought I was getting underruns, but adding some logging suggests that's not actually the case. Maybe what I'm seeing will shed some light on things in this case, or maybe it's something else.
Basically when the app is running, which is often at night with bedside mode engaged in the clock app (or from the lock screen), every so often I'd get a very brief glitch, a dropout in the sound on the order of 50ms or so (just guessing at that, but it's surely less than 200ms and more than 10ms).
After starting to experiment with thread priorities, first at 20 (default is 10) then 30, then 40, I happened to be monitoring it with the clock app running, with its active frame showing. The glitch is synchronized with the active frame updating as the minute hand ticks forward.
It happens only maybe one time in 5 or 10, so it takes a while to observe it. It's always synchronized to the 60-second rollover of the system clock, however. Not sure yet if it happens only with the clock app or bedside mode actually running.
I'm now at priority = 50 and no sign of the glitch in the last 20 minutes or so. Not conclusive but I'll post more later, or likely start a new thread since I don't seem to be having actual underruns. Something's interfering with the interrupt processing, I think.
